Method of treating objects



March 17, 1931. A. H. ADAMS METHOD OF TREATING OBJECTS Filed Nov. 19. 1927 Wren/0r j/f/rw/i Add/77.5

. Patented Mar. 17, 1931 A I UNITED STATES ARTHUR HERMAN ADAMS, OF LA GRANGE, ILLINOIS, ASSIGNOR TO WESTERN ELEC- TRIO COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OI NEW.

YORK

mnrnon or TREATING omnc'rs Application filed November 19, 1927. Serial No. 234,361.

-This invention relates to a, method of. treating objects, and more particularly to a method of applying coating material to objects. The object of this invention is ,to provide an improved method 'of treating ob ects in an expeditious and economical manner to provide a smooth, uniform coating.

'It is believed that a complete understanding of the improved method will be procured from a description of one embodiment of an apparatus by means of which the.

method may be practiced to uniformly and smoothly coat small objects with a metallic material.

In accordance with the aforementioned object one embodiment of an apparatus-by -means of which the method may be practiced comprises a freely rotatable basket containing loosely arranged objects to be coated, which is designed to be immersed in a bath of molten tin, zinc, alloy, wax, pitch, or other coating material. The bath, which may be tin, is contained in a rotatable receptacle provided with an enlarged portion.

When the receptacle is rotated, motion is also imparted to the perforated basket through the bath of molten tin, and when a certain speed is attained the major partof the tin is gradually thrown outwardly, due

[to the action of centrifugal force as speed is acquired and collects in the enlarged portion of the receptacle, leaving the perforated basket entirely free of the bath of tin. During this stage of the operation thebath of molten tin gradually recedes from the objects in the basket, removing as it recedes all excess tin by the combined effect of the surface tension of the bath of tin and of centrifugal and gravitational forces, thereby resulting in a smooth and uniform coating. The effect is the same as though a has.

ket of objects was withdrawn from a bath of'tin in a much greater gravitational'field than the earth affords.

Other objects and advantages of this in vention will more fully appear from the following detail description taken in connection with the accompanying drawings which illustrate one embodiment of an apparatus by means of which the method may be practiced,in.which Fig. l'is a fragmentary plan view of an apparatus embodying the features of this invention I Fig. 2 is a vertical section, partly in elevation, taken on the line 2-2 of Fig. 1,and Fig. 3 is a fragmentary detail section through the vertical axis of the basket which holds the objects.

Referring now to the drawing in detail wherein. like reference numerals indicate similar parts, and particularly to Fig. 2, a

circular base 10 rotatably supports .by means of suitable antifriction bearings a circular receptacle l1. Attachedto a lower reduced bearing portion' of the receptacle 11 is a worm gear 12 which meshes with a worm 13 which may be driven from a suitable source of/power (not shown). The receptacle 11 is provided with an enlarged portion 14 at itsupper end, the purpose of which will become apparent as this description progresses, the portion 14: having an axial opening 15 at its top surface. I

Coaxially arranged with and rigidly supported above the receptacle 11 is a nonrotatable shaft 18 whichis adapted to be reciprocated in a vertical direction by any suitable means (not shown), for instance a hydraulic cylinder. Rotatably mounted upon the lower end of the shaft 18 by. suitable anti-friction bearings is a sleeve 19, a head 20 of the. shaft holding the sleeve thereon. The sleeve 19 is provided in the present instance with three outwardly and downwardly extending arms or spiders 21.

Suspended from the free ends of the spiders 21 is a circular basket 23 formed of sheet metal havingits vertical and lower walls erforated, the whole being strengthened y a plurality of metal bands 24, the upper endsof which extend above the top edge of the basket and above .a normal-immersion level 25 of the molten tin or other coating vmaterial. The freefends of the spiders 21 are attached to the upperends of the bands 24 by suitable readily releasable means.

The sleeve 19 is of such a lengththat taken with the three spiders 21, the basket 23 1s maintained sufficiently rigid upon the shaft 18 in the operation of the apparatus that no appreciable lateral movement of the basket within the receptacle 11 occurs. The receptacle 11 is provided with a plurality of circularly and uniformly arranged ribs 26,extending from its inner peripheral wall to- Ward the axis thereof and spaced from the peripheral surface of the basket 23- sufficiently. to not interfere with its free rotation. In addition to one purpose of the ribs 26 which will be described hereinafter in the description of operation of the apparatus, they also serve as ameans to steady the basket 23 during its rotation and facilitate the uiding thereof through'the opening 15 0% the receptacle, and into the ring guard 33 when it is being withdrawn from the receptacle.

Removably attached-at its'lower end to the basket 23 within an opening formed axially in the lower perforated wall thereof is an imperforatewall tube 27, the opening in its lower end having a screen or siege 28. The tube 27 is removably secured in posi tion in the basket 23 by inserting the lower end thereof in ajsleeve 29 (Fig. fixed to the bottom wall of the basket within the axial, opening thereof. The upper end of the tube 27 is flared and lies flush with the upper edge of the basket 23. The purpose of the tube 27 in-the operation of the apparatus serves as a depository for dross or other foreign matter contained in the bath, which in the centrifuging action,is attracted to the axis of the rotating parts by the vortex created and flows into the flared mouth of the tube and is retained at the bottom thereof by the sieve 28, any molten metal H passing therethrough.

Surrounding the lower reduced portion of the receptacle 11 is I an oven 30 provided. with a plurality of nozzles 31 for. projecting against the sides of'the receptacle gas flames to maintainthe tin and the objects to be coated at a sufficiently high temperature to facilitate the vflow of the metal around the objects to thoroughlyenvelop them and in the centrifuging action the removal of all excess metal therefrom. Attached to the ,walls of the oven 30 and surrounding the enlarged portion 14 of the rotatable receptacle 11 is a housing or guard 32 provided at its upper end with a collar portion 33, the diameter of which'is sufliciently large to receive the basket 23 when it is raised from the receptacle 11 during the centrifuging rotating basket is raised from thereceptacle 11. Substantially one-half of the portion 33 maybe swungz'open about a hinge 34 to Upon the rotating basket 23 reaching the.

dotted line position thereof a circular brake surface 37 formed upon the upper end of the sleeve 19 engages a stationary friction member 38 which may be supported in a suitable manner by a standard (not shown) fixed to the floor. The member 38 is ring shaped but cut open on one sideto permit theshaft 18 with the basket 23 to be swung to one side as described hereinbefore. Thus the basket 23 is quickly brought to a stop upon reaching its upper position. In practicing the method of metal coating small objects with the hereinbefore described apparatus the bath of tin contained temperature in themanner and for the purpose hereinbeforedescribed. The bath of tin is then skimmed of .any surface impurities and the basket 23 with the objects therein is lowered into the bath and when the basket has been completely submerged the in the receptacle 11 is brought to a suitable receptacle 1 1 is caused to rotate. The speed i of rotation of the receptacle 11 maybe increased very rapidly by the normal acceleration of a motor or belt driving it through the worm 131 The bath of tin will accelerate more gradually, due to its friction on the walls of the receptacle 11. The ribs 26 of the receptacle 11 it will be apparent serve to facilitate the rotation of the bath of tin around the-basket 23 and thus the latter is caused to rotate with it. In fact, the bath can not rotate much more rapidly than the basket, due to the surface friction created between the mass of tin, the basket and the mass of objects therein. As the velocity of the bath and basket increases the centre of the bath collects the lighter or surface slag and impurities and the crater of the intersected by the flaring top edge of the tube 27, thus segregating these impurities so they cannot descend with the clean metal and be deposited on the objects in the basket. Just after this occurs, and not before, the level of the tin reaches, the height ofthe objects in the basket 23, it is well to further cleanse the surface of the bath by sprinklingit with a flux, such as rosin, tallow, any very high .flash paint-oil, ,orwith dry zinc chloride or ammonium chloride. The specified fluxes are particularly adapted for use with .surface is finally lowered sufliciently to be 1 baths of tin and when other baths are em- 1 selected. The impurities will be'intercepted by the tube 27 and confined within that tubeuntil the central level of the bath is lowered to a point just below the screen 28, where" all but the finest of the slag and impurities will be deposited. The tube 27 as hereinbefore described is removable so that.

the slag and impurities may be readily removed therefrom and the screen 28 cleaned. The screenQS is preferably cleaned at the end of each cycle of operation, just before fresh objects to be treated are put in the basket 23.

In the meanwhile, as the surface of the bath takes the well known form of a paraboloid of revolution of increasingly sharp curvature, indicated by the broken line 39,

V the tin overflows progressively past the knee or corner of the receptacle 11, into the upper-and outer. enlarged portion 14 thereof. Obviously as this process continues the bath flows very gradually away from the basket and the therein contained objects, its surface moving through them both downwardly and outwardly, forming 'in the lower part of" the receptacle 11 successively paraboloids of revolution. It will be noted that each drop of tin on any object near the surface of the ulled in a direction normal to that surface y the resultant of centrifugal and gravitational forces. It will be noted that the surface-tension of this receding surface is also in this same direction. The method and apparatus of the present invention is particularly useful in that the last drop on any outward" edge or corner of an object,

which is very hard to throw 0d and which is likely either to remain or make a lump when cold or dry, or to fly off and spatter up others of the mass of objects is removed due to the additive stripping efieetof gravity, centrifugal force and surface tension.

Also since it is not necessary to remove the objects from the effects of the hot bath, additional heat is not required to keep the metal or material on their surface. uniformly hot and free flowing and the formation of oxides and slags is thereby prevented.

It will be clear that, as soon as the bath has attained the speed of thereceptacle 11, which can be determined in a number of ways, as by the power consumption going down, cessation of power loss in fluid friction, or by a simple observation through the top openmg by a mirror, or more practically by noting once and for all the time it takes, there is no further advantage in con tinuing to revolve the basket 23, but rather a danger of cooling the parts and of sticking them together. The basket then should be raised to the position shown in dotted lines inside of guard ring 33, and its rotation should befistopped as quickly as possi-' ble, which may be accomplished through theuse of the brake surface 37 engaging the stationary friction member 38.

The power should be cutoff from worm 13 and the receptacle l1 allowed to come to rest. The bath therein will also come to rest and become level, which is facilitated,

itnvill be apparent, by the ribs 26 of the the basket is refilled, or another one already filled with objects ready for coating may be used, and replaced on the spider and then subjected to the molten bath which has been prepared in the manner previously described.

Although this invention has been disclosed and described in connection with the coating of small objects with tin, it willbe understood'that the invention is capable of other applications and is only to be limited by the scope of the appended claims.

dWhat is claimed is:

1. A method of treating objects which consists in subjecting the objects to a treat ing material, and effecting a relative move ment between the objects and the treating material while the objects. are subjected to the material to remove excess material from "the objectsby the combined action of centrifugal force and surface tension.

2. A. method of treating objects which consists in subjecting the objects to a treat ing material, and efiecting a relative movement between the objects and the treating material while the objects are subjected to the material to removeexcess material from the objects by the combined action of centrifugal and gravitational forces.

3. A. method of treating objects which consists in subjecting the objects to a treating material, and effecting a relative movement between the treating material and the objects while the objects are being treated to cause the treating material to establish a hollow formation free of the objects.

4%. A method of treating objects which consists in subjecting the objects to im- Inersion in a treating material, and efi'ecting a relative movement between the treating material and the objects while the ob jccts are immersed to cause the treating material to establish a parabolic formation free of the objects.

5. A method of applying coating material to objects which consists in subjecting the objects to immersion in the coating material, and then centrifuging the residuary coating material free from the objects while maintaining the objects at their normal immersion level in the coating material.

6.. A method of applying coating material to objects which consists in subjecting the lltl centrifuging the residuary coating material free from the objects, and then withdrawing the coated objects from their normal immersion level in the coating material.

7. A method of applying coating material to objects which consists in subjecting the objects to immersion in the coating material,

centrifuging the residuary coating material free from the objects and-causing a' revolving of the latter about the axis of the material, and then withdrawing the coated objects from the normal immersion level of the material, the inertia of the objects causing them to continue to rotate whereby centrifugal force'and surface tension removes any excess material therefrom.

, 8. A method of treating objects, which consists in subjecting the objects to immersion in a treating material, and efiecting a rotary movement of the material while the objects are subjected to the material in their normal immersion level therein 'to remove excess material from the objects by the combined action of centrifugal force and surface tension. v

9. A method of treating objects, which consists'in subjecting the objects to immersion in a treating material, and efiecting a rotary movement of the material and the objects while the objects are subjected to the material in their normal immersion level therein to remove excess material from the objects by the combined action of centrifugal force and surface tension. 1 In witness whereof, I hereunto subscribe 111271131116 this 9th day of November A. D., 19

.ARTHUR HERMAN ADAMS. 

